In an ordinary electrophotographic process, a photosensitive drum of the electrophotographic apparatus is electrostatically charged and image-exposed to form latent images, the latent images are imagewise developed using toners, and after transferring the toner images onto a transfer paper, the remaining toners on the drum are recovered by cleaning to reuse.
As the cleaning method of the remaining toners on the drum, a method of contacting a cleaning blade composed of a rubber material such as a urethane rubber, etc., onto the surface of the photosensitive drum is generally used. In such a blade cleaning method, as a matter of course, an inferior cleaning for insufficiently removing the remaining toners must be prevented and furthermore, the cleaning blade must be designed to prevent the occurrence of troubles such as an abnormal sound (sliding sound) of the cleaning blade, turning of the blade, etc.
Now, as the evaluation of the cleaning results, there are not only the evaluation of the cleaning property during ordinary use but also the problem occurred at initially rotating the photosensitive drum by contacting thereto the cleaning blade.
That is, in the initial state, toners do not exist on the surface of the photosensitive drum and hence the cleaning blade is directly contacted with the photosensitive drum, whereby the friction resistance is very high. When the photosensitive drum is rotated in such a state, it sometimes happens that the surface of the photosensitive drum and the edge of the cleaning blade are damaged by the friction and also the rotation of the drum becomes impossible due to the cleaning blade.
Hitherto, for preventing the occurrence of such problems, a method of attaching a proper lubricant powder to the photosensitive drum and/or the cleaning blade is first practiced. Such a lubricant powder is called as a cleaning assistant, or a cleaning aid, and a powder of TEFLON or polyvinylydene fluoride (KAINER, trade name, made by Penwalt Co.) has been used.
However, it has been found that when the photosensitive drum is rotated using the conventional cleaning assistant as described above, the cleaning assistant itself is strongly negatively charged, which results in causing the problem that the surface of the photosensitive drum is positively charged. When an organic photosensitive drum (hereinafter, such is referred to as an OPC drum), which is negatively charged, is used as the photosensitive drum, the positive charge is not discharged. As a result, the positive charge remains on the surface of the photosensitive drum for a long time to cause a defect in the image formation. This phenomenon is called a charge memory and in the case of using a packaging material for the photosensitive drum, it is required to use a packaging material causing the frictional charge having the same polarity as the charging polarity of the photosensitive drum as described in JP-A-64-70785 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). This shall be the same in the case of the cleaning assistant.